Tuesday, 28 April 2020

Bacteria on the International Space Station no more dangerous than earthbound strains

Shortly
after the National Aeronautics and Space Administration (NASA) installed the
water dispenser aboard the ISS in 2009, periodic sampling showed that two
bacteria, Burkholderia cepacia and later on, Burkholderia contaminans
were contaminating the drinking water. These microbes belong to a group of
related Burkholderia species that cause opportunistic lung infections in
people with underlying health conditions and are very difficult to kill using
common sterilization techniques. The bacteria have persisted in the water
dispenser despite periodic flushing with an extra-strength iodine cleaning
solution.

To
learn more about these bacteria, researchers sequenced the genomes of 24
strains collected from 2010 to 2014. All of the B. cepacia and B.
contaminans strains were highly similar, and likely descended from original
populations of these two bacteria that were present in the water dispenser when
it left Earth.

The
researchers conclude that the two bacterial species living within the dispenser
are no more dangerous than similar strains that might be encountered on Earth.
In the event of an infection, the bacteria can still be treated with common
antibiotics.

The
authors add: "Within each species, the 19 B. cepacia and 5 B.
contaminans recovered from the ISS were highly similar on a whole genome
scale, suggesting each population may have stemmed from two distinct founding
strains. The differences that can be observed among the isolates of the same
species are primarily located within putative plasmids. We find that the
populations of Burkholderia present in the ISS PWS are likely are not
more virulent than those that might be encountered on planet, as they maintain
a baseline ability to lyse macrophage, but remain susceptible to clinically
used antibiotics."